Open AccessSix1 Promotes Epithelial-Mesenchymal Transition in Bronchial Epithelial Cells via the TGFβ1/Smad Signalling Pathway
Author(s) -
Wenxin Wang,
Zhaochuan Yang,
Meixiang Li,
Zhenhong Wang,
Yanchun Shan,
Zhenghai Qu
Publication year - 2021
Publication title -
international archives of allergy and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 100
eISSN - 1423-0097
pISSN - 1018-2438
DOI - 10.1159/000512873
Subject(s) - epithelial–mesenchymal transition , smad , transforming growth factor , transforming growth factor beta , cancer research , fibronectin , vimentin , microbiology and biotechnology , immunohistochemistry , biology , chemistry , immunology , downregulation and upregulation , extracellular matrix , gene , biochemistry
The homeodomain transcription factor sine oculis homeobox homolog 1 (Six1) plays a crucial role in embryogenesis and is not expressed in normal adult tissue but is expressed in many pathological processes, including airway remodelling in asthma. The current study aimed to reveal the effects of Six1 in regulating the airway remodelling and its possible mechanism. Methods: A mouse model of ovalbumin-induced asthma-associated airway wall remodelling and a bronchial epithelial cell (16HBE) model of transforming growth factor β1 (TGFβ1)-induced epithelial-mesenchymal transition (EMT) were used to investigate the role of Six1. Then, 16HBE cells were transformed with Six1 expression vectors and treated with a TGFβ1 pathway inhibitor to determine the role of Six1 in EMT. The effect of Six1 and its possible mechanism were assessed by immunohistochemistry, RT-PCR, and Western blot. Results: Six1 expression was elevated in the lungs in an OVA mouse model of allergic asthma and in 16HBE cells treated with TGFβ1. Six1 overexpression promoted an EMT-like phenotype with a decreased protein expression of E-cadherin and increased protein expression of α-smooth muscle actin (α-SMA) as well as fibronectin in 16HBE cells; these effects appeared to promote TGFβ1 and phospho-Smad2 (pSmad2) production, which are the main products of the TGFβ1/Smad signalling pathway, which could be reduced by a TGFβ1 inhibitor. Conclusion: These data reveal that Six1 and TGFβ1 are potentially a part of an autocrine feedback loop that induces EMT, and these factors can be reduced by blocking the TGFβ1/Smad signalling pathway. As such, these factors may represent a promising novel therapeutic target for airway remodelling in asthma.